There are no news stories that catch the eye of the British press quite like bad news stories from the NHS. There are no worse news stories about the NHS than those of unnecessary deaths – and there has been a glut recently. In February it was the Francis report into Mid Staffordshire NHS Foundation Trust. Then it was the Keogh report. In between, the British Medical Journal published a research paper showing that death rates after elective operations at weekends were higher than those following operations during the week.

But not every death makes it into a report.

Let's go back a few years. It's a morning ward round in a London hospital in the late 1990s. I'm the registrar on a medical unit and we've been on call since 9am the previous day. The patient in front of us, whom I'm seeing for the first time, is in her 80s, diabetic, with a history of heart disease. She has been admitted overnight and the senior house officer did not call for help. Apparently, he thought he knew what he was doing.

Turns out that he can't tell pneumonia from heart failure. It isn't always easy. The blurred x‑ray of one can look much like the other. Before I even examine her, I can see she is in a bad way. Blue lips, stertorous breathing. Her kidneys are probably already in failure but there is no way to be sure because the senior house officer hasn't asked anyone to monitor her urine output.

Two days later, I write her death certificate. To be fair, with her underlying diabetes and heart disease, who is to say that if she had been put on antibiotics right away the outcome would have been any different. But I still remember her face. I don't remember the senior house officer's.

This was before the introduction of the European working time directive, which limits working hours to 48 per week and requires minimum rest periods between shifts. Despite becoming law in the UK in 1998, it wasn't until 2004 that it was extended to NHS doctors.

Before that, a routine weekend shift, which we would normally do every three or four weeks, began at nine on Saturday morning and ran through to nine on Monday morning, followed by a normal eight hour Monday workday. That's 56 hours. We each had a room with a bed, but no guarantee that we would get to use it. If we did, it often wasn't for more than an hour or two at a time.

I remember working in one hospital where some bright spark in admin had come up with the idea of running the weekend shift from 9am on Friday, saving us the inconvenience of going home to sleep on Friday night. Ending at 5pm on Monday, that was 80 hours straight.

We should be clear about what we're talking about here. Subjecting a human being to 56 hours without any rest period, let alone 80 hours, is torture. Don't imagine that you can conceptualise what it's like if you've never done it. If we had been prisoners rather than doctors, Amnesty International would have been campaigning on our behalf.

It didn't do much for standards of patient care, either. In my experience, it wasn't simple errors that were made. Somehow, no matter how tired you were, you could manage to calculate a drug dose. If you couldn't, a nurse would usually point out when you had left out a zero or added one too many.

No, it was more subtle than that. It was a matter of not going to assess a patient because you were just too tired and persuaded yourself they'd be all right. It was not calling for help if you did go to assess that patient, because, like that senior house officer from that ward round long ago, you mistakenly thought you knew what was going on – kind of – and the person you would have to call might have been asleep.

The senior house officer wasn't censured. No one even thought of it. Things like that were happening so often that there wouldn't have been a junior doctor left standing if action had been taken.

Besides, was he negligent, incompetent, inexperienced, or as much as victim of the system as the patient he failed to diagnose? You would be surprised how powerful the unspoken taboo of waking anyone else was. On the other hand, if you have ever worked an 80-hour shift, you would not be surprised at all.

We mismanaged, harmed and – let's face it – allowed patients needlessly to die because of inexperience compounded by fear of unnecessarily waking someone else in a world of mutually assured exhaustion.

In January of this year, David Cameron poured a new year's bucket of cold water over Britain's workers by saying that the European working time directive should never have been introduced. Why? Because "it's actually affecting the way we run our hospitals".

There are plenty of things that can go wrong in the NHS, as the Francis and Keogh reports demonstrate. But being treated by doctors who are too sleep-deprived to care, mercifully, is no longer one of them.

If Cameron thinks that by going back to that world we will make things better, then I suggest that the next time he needs a trip to hospital, someone find him a junior doctor who has been working in the relevant speciality for all of two weeks, has been awake for 48 hours, and is too scared to pick up the phone and wake someone who might actually know what they're doing. Because that's what the rest of us will be facing.